Backing-out punch



E. S. ASTIN.

/ BACKING OUT PUNCH.

APPLICATION man SEPT. 15, 1919.

1,862,91 1, H Patented Dec. 21, 1920.

Inventor;

Ern t JZAatin,

ERNEST SHERWOOD ASTIN, OF BALTIMORE, MARYLAND,

AssIGNoR TO THE LIBERTY TOOL COMPANY, OF BALTIMORE, MARYLAND, A CORPORATION OF MARYLAND.

BACKING-OUT PUNCH.

Specification of Letters Patent. Pat gntd D c 21 1}2() Application filed September 15, 1919. Serial No. 323,?52.

To all whom it may concern:

Be it known that I, ERNEST S. AsrIN, a citizen of the United States, and resident of Baltimore, Maryland, have invented certain new and useful Improvements in Backing-Out Punches, of which the following is a specification.

The invention is for use with pneumatic hammers and relates to a backing out punch for driving rivets out of holes in dismantling any riveted structure.

It consists of the features and combination of parts hereinafter described and particularly pointed out in the claim.

In the accompanying drawings,

Figure 1 is a view of a pneumatic hammer with my improvement combined therewith.

Fig. 2 is a view of the punch detached, and

Fig. 3 is a view of the bushing.

In these drawings 1 indicates a pneumatic hammer of ordinary form, 2 indicates a backing out punch, and 3 indicates a bushing which externally is of cylindrical form to fit a recess 4: formed in the interior of the end portidn of the hammer barrel pressing a shoulder 5 against which the bushing is seated. This bushing has a conical opening tapering toward the inner side of the hammer barrel and this tapered opening provides a seat for receiving the shank 6 of the punch 2 which shank is tapered to fit the conical seat of the bushing. The punch also tapers from its central part 7 toward its front end 8.

Backing out punches as heretofore constructed have been made with a tapered front end, a shank of cylindrical form and a main central body portion of greater diameter than the shank providing a shoulder intermediate the shank and the body portion. This old form of backing out punch is liable to breakage particularly at the intermediate shoulder and at points along its tapered front end. This breakage is due to the crystallization of the metal resulting from the rapid blows delivered by the punch. With my improvement there is no abrupt shoulder between the fore part of the punch and its shank portion, but a long bearing face is provided between this bearing face being tapered and accurately fitting along the tapered seat within the bushing a so that the strain resulting from the force of the blows will be dis tributed along this face and taken by the bushing, which being surrounded by the wall of the hammer barrei throughout its length, will resist any breaking tendency and the thrust will be taken by the shoulders 5 within the hammer.

I claim as my invention:

A backing out punch for use with pneumatic hammers comprising a punch member tapered from its central portion all the way to its front and rear ends and a bushing having an opening tapered throughout provid ing a seat for the tapered shank portion of the punch member or the tapered front part when the punch is reversed, substantially as described.

In testimony whereof I affix my signature.

ERNEST SHERWOOD ASTIN.

the points a: and y 

